1. Field of the Invention
The present invention relates to the field of treatment of oral tissues using laser radiation of an especially effective wavelength and having a handpiece with means for delivery of this laser radiation and for spraying a liquid/gas mixture onto the treatment area to improve the treatment effects.
2. Information Disclosure Statement
A variety of laser treatments are used in the field of oral and maxillofacial surgery. Such treatments offer many advantages, especially because of their high coagulation properties, high incision quality, and post-operative benefits for the surgeon and the patient.
Depending on the wavelength, energy levels and radiation patterns used, the effects of laser radiation on tissue are significantly different. It is a goal of the present invention to achieve fast, non-carbonized, aesthetic surgical effects, with a limited coagulation zone in a largely non-traumatic manner with minimal or no bleeding.
During treatment, laser light heats tissue due to the absorption of energy by water molecules in the tissue, thereby destroying living cells and resulting in coagulation of the tissue for excisions or incisions. During treatment, it is essential to avoid overheating or damaging surrounding tissue and to control the effects of the radiation. The deeper the radiation penetrates the tissue, the less controllable are the resulting heat effects. Residual heat may affect the nerve of the tooth causing pain to the patient and may cause tissue to carbonize and become necrotic. Thus, it is desirable to minimize transmission of conducted heat to underlying and surrounding tissue. It is therefore desirable to accurately control the amount of light energy transferred to the tissue to be treated. The amount of energy must be sufficiently controlled so that local tissue is effectively treated and surrounding tissue is not heated by residual energy.
In WO 99/39652, it is described how to treat periodontal pockets with laser light without heating the surrounding tissue by spraying a coolant of mixed water and air onto the tissue. The device used comprises a handpiece with a combined water and fiber duct whereby the spray is generated at the output end of the handpiece. However, this disclosure does not teach how to avoid unwanted heating of deeper tissue layers. Moreover, the invention provides for conducting the laser delivery fiber and the water in one duct. This configuration is disadvantageous because the water at the fiber tip absorbs laser energy and thus renders the energy delivered to the tissue undeterminable, and moreover, the tip heats up and can cause unwanted burnings. Further the position of the fiber and therefore the aiming of the laser light is not defined. Also, WO 99/39652 mandates the use of a xe2x80x9cwavelength that is moderately absorbed in waterxe2x80x9d. The invention claims the use of wavelengths ranging from 1-1.2 microns or 1.06 to 1.07 microns, which are moderately absorbed in water. Using wavelengths that are more highly absorbed in water would presumably lower the effectiveness of the treatment and is therefore avoided.
U.S. Pat. No. 5,374,266 describes a laser device consisting of a handpiece with a special fiber and fiber duct for small cavities and uniform irradiation. This device features a cooling fluid spray that is fed along the fiber probe to clean the treatment area and cool the fiber probe after irradiation or to cool the probe during irradiation. The water is then blown peripherally from the probe so as to avoid any moisture damage to the probe fiber. Thus, the use of water in this invention is for cooling the probe, not the treatment site during irradiation.
In general, the prior art has contemplated the use of cooling liquid or sprays in conjunction with irradiation treatments to avoid thermally damaging surrounding tissues. However, only certain wavelengths have been described as effective for use in conjunction with liquid cooling means. Those wavelengths are those that are not highly absorbed in water. Indeed, as seen in WO 99/39652, the prior art contemplates the use of wavelengths, such as those on the order of 1 micron, that have relatively low absorption in water so as not to inhibit treatment. In addition, U.S. Pat. No. 6,129,721, although describing an irradiation handpiece featuring a fiber and delivery means for spraying fluid and gas that would at first seem similar to the present invention, limits its invention to those wavelengths between 1 and 5.5 microns.
U.S. Pat. No. 5,290,274 by Levy et al. describes the use of radiation with two different wavelengths in conjunction with a step of directing cooling fluid to the treatment site during irradiation. The first wavelength is between 0.7 and 1 micron, and the second wavelength is in the vicinity of 3 microns. Levy claims that the use of Nd:YAG radiation in combination with a liquid cooling source is effective, because fundamental frequency radiation with a wavelength of 1.06 microns and frequency doubled radiation with a 0.532 micron wavelength are essentially not absorbed in water. However, according to Levy, the effectiveness of an Er:YAG laser is considerably reduced when used in conjunction with a cooling liquid spray because it produces radiation of a wavelength that is highly absorbed by water.
As can be seen by the above-described prior art, the prior art teaches that the use of a wavelength that is highly absorbed by water, such as a 980 nm laser, in conjunction with a liquid cooling spray would be ineffective.
The present invention addresses the above mentioned drawbacks of the prior art by providing a method and system that avoids unwanted heating of surrounding tissue by different means and provides a very precise incision quality by a combination of laser light of a wavelength of approximately 980 nm and a cooling liquid spray. Preferably, pulsed laser light is used to provide localized energy deposition and heating, therefore avoiding unwanted heating of underlying tissue. Additional liquid spray flushes away tissue debris and provides additional cooling of treated tissue.
An object of the present invention is to provide a system and method for improved treatment of oral tissue using laser light and without heating the surrounding tissue and without carbonization.
Another object of the present invention is to avoid unwanted tissue heating and significantly improve treatment results by using an advantageous wavelength for irradiation and by spraying a liquid/gas mixture onto the tissue.
Still another object of the present invention is to use laser light of a wavelength of 980 nm.
Yet another object of the present invention is to provide a handpiece with a laser fiber duct and liquid/gas ducts.
A further object of the present invention is to provide a handpiece with a changeable sterile fiber tip.
Briefly stated, the present invention provides a system and method for improved treatment of oral tissues using 980 nm laser radiation and a handpiece with means for concurrently delivering the laser radiation and a liquid/gas spray onto the treatment area to improve the treatment effects. Unwanted heating and carbonization of surrounding tissues is reduced. The liquid/gas spray may be mixed inside the handpiece or in a separate device. The combination of cooling sprays with radiation wavelengths having high absorption in water has previously been avoided due to the thought that energy absorption by the cooling fluid would render the energy delivered to the tissue uncontrollable and of minimal benefit. Preferably, pulsed laser light provides a localized energy deposition and heating to avoid unwanted heating of underlying tissue. The liquid spray flushes way tissue debris in addition to cooling the treated tissue.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, (in which like reference numbers in different drawings designate the same elements.)